* Possibly "I was the cause" in French. Or maybe it's "une du jeux la," "it's just a game"? General consensus seems to be Hachi sucks at French.
** This line is ever-so-slightly different in the lyrics on Hachi's blog. A more accurate translation that sorta covers both would be "You're now alone in the audience."
*** CLICK FOR PRETENTIOUS! ANALYSIS

What, you want an analysis, do you? Who the heck does analyses of PLAYS?
So, she gets involved in a "play" where she has to "put on an act" for the guy she loves. She knows it's just a "fairytale world," but forgets about it as "his hands" effectively control her. (The mention of hands in particular makes it hard for me to see that line any other way.)
Even if she realizes it, she's stuck in it: she can't untangle the red string (general metaphor/symbol for lasting relationships) from the wiring (the mess she's made in "acting" for him). This could even mean she can't tell the difference between the two.
While she only mentions one on her pinky, I imagine Hachi may have been going for an image of her as a puppet being pulled by many red strings, making her totally dependent on the one she loves but is metaphorically controlled by.
Since the act seems to be to no end - the guy isn't giving anything back - there's, in her eyes, "no audience." Later she realizes that he HAS to be an audience, or else... well, the ending happens.
(And since she says the only audience "left," it seems anyone else looking on doesn't matter to her anymore, or just stopped paying attention, taking away even more of the meaning she has to her life besides him.)
The line that gets caught in her throat could just be "I love you," and she's afraid of rejection (which she apparently receives after just up and kissing him, and, well, see what happens then).
She could be blaming herself in French either because she believes it's her fault he doesn't love her and/or because she orchestrated all the "acting" nonsense (whether she really did or not).
By the way, PLAY THE UNE DUE JE LA PART BACKWARDS AND PART OF CLOCK LOCK WORKS KEEPS REPEATING WHAT THE?!
"Can you remember your first line?" could imply that she isn't sure when the act really started (or it started a really, really long time ago) and how much of her life has been wasted.
Alternatively, it could imply that things were different back when it started, and he figures Mikola must not remember the first thing she said to him if she's doing all this.
Or, since the "your" is actually just implied, it could have been something he told her at the very start about how their relationship would go, but that doesn't fit as well if all the "acting" is Mikola's idea.
Someone on Nico brought up a blurring of fantasy and reality, perhaps explaining things like the wolf and maybe even how she ended up with the pistol.
Serious analysis aside, a theory maybe too outrageous even for Hachi: Mikola's suicide by gun to the head is a link between contemplating suicide in clock lock works and Alice doing the Persona 3 gun-to-head pose in the Persona Alice PV.